Fiedler K, Simons K
Cell Biology Programme, European Molecular Biology Laboratory, Heidelberg, Germany.
J Cell Sci. 1996 Jan;109 ( Pt 1):271-6. doi: 10.1242/jcs.109.1.271.
VIP36 was isolated from MDCK cells as a component of glycolipid-enriched detergent-insoluble complexes. The protein is localized to the Golgi apparatus and the cell surface, and belongs to a new family of legume lectin homologues in the animal secretory pathway that might be involved in the trafficking of glycoproteins, glycolipids or both. Here we show that VIP36 is N-glycosylated and expressed in organs abundant in epithelial cells as well as in non-epithelial organs. Our studies demonstrate that the recombinant exoplasmic/luminal domain of VIP36 binds Ca2+ and that the protein decorates internal membrane structures of MDCK cells in vitro that are distinct from the Golgi apparatus. This binding requires Ca2+ and can be specifically inhibited by N-acetyl-D-galactosamine. The recombinant protein was used for affinity chromatography. Glycopeptides obtained from [3H]galactose-labelled cells bind to VIP36 and can be eluted with N-acetyl-D-galactosamine. Our data imply that VIP36 functions as a lectin in post-Golgi trafficking.
VIP36是从MDCK细胞中分离出来的，作为富含糖脂的去污剂不溶性复合物的一个组分。该蛋白定位于高尔基体和细胞表面，属于动物分泌途径中豆科植物凝集素同源物的一个新家族，可能参与糖蛋白、糖脂或两者的运输。在这里，我们表明VIP36是N-糖基化的，并且在上皮细胞丰富的器官以及非上皮器官中表达。我们的研究表明，VIP36的重组胞外/腔内结构域结合Ca2+，并且该蛋白在体外修饰MDCK细胞中与高尔基体不同的内膜结构。这种结合需要Ca2+，并且可以被N-乙酰-D-半乳糖胺特异性抑制。重组蛋白用于亲和层析。从[3H]半乳糖标记的细胞中获得的糖肽与VIP36结合，并且可以用N-乙酰-D-半乳糖胺洗脱。我们的数据表明VIP36在高尔基体后运输中作为凝集素发挥作用。
